Kanye was hospitalized at UCLA Medical Center for exhaustion last November -- shortly after canceling his remaining Saint Pablo tour dates -- and was released nine days later. A source close to 39-year-old Kanye told ET on Sunday that instead of attending this year's Met Gala, the "All Day" rapper would be at home with his 3-year-old daughter, North, and 1-year-old son, Saint.

"He's staying in Los Angeles with the kids," the source said. "He's just tending to the family right now and taking time off from public events."

Kim and Kanye have attended the Met Gala together every year since Kim's Met Gala debut in 2013. She noticeably toned it down on Monday night, opting for a simple white Vivienne Westwood dress and wearing no jewelry.

"I was definitely materialistic before, not that there's anything bad with having things and working hard to get those things, and I'm really proud of everyone around me that's successful," she explained. "But I'm so happy that my kids get this me, and that this is who I'm raising my kids [to be]. Because I just don't care about that stuff anymore, I really don't."